A merchandise sales data processing apparatus includes a code reading unit configured to read a code of a customer purchasing a merchandise, an electronic receipt issuing instruction unit configured to receive an instruction for issuing electronic receipt information associated with merchandise sales data, an electronic receipt generation unit configured to generate the electronic receipt information in correlation with the code of the customer when the instruction for issuing the electronic receipt information is received by the electronic receipt issuing instruction unit, a transmission unit configured to transmit a company code indicating a company and the electronic receipt information generated by the electronic receipt generation unit to an electronic receipt server, and a receipt printing unit configured to print a paper receipt associated with the merchandise sales data when the instruction for issuing the electronic receipt information is not received by the electronic receipt issuing instruction unit.